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Versions: (draft-qin-softwire-multicast-prefix-option) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 RFC 8115

Softwire WG                                                 M. Boucadair
Internet-Draft                                            France Telecom
Intended status: Standards Track                                  J. Qin
Expires: September 26, 2014                                        Cisco
                                                                 T. Tsou
                                               Huawei Technologies (USA)
                                                                 X. Deng
                                                                   APNIC
                                                          March 25, 2014


  DHCPv6 Option for IPv4-Embedded Multicast and Unicast IPv6 Prefixes
             draft-ietf-softwire-multicast-prefix-option-06

Abstract

   This document defines Dynamic Host Configuration Protocol version 6
   (DHCPv6) Option for multicast transition solutions, aiming to convey
   the IPv6 prefixes to be used to build unicast and multicast
   IPv4-embedded IPv6 addresses.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 26, 2014.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  PREFIX64 DHCPv6 Option  . . . . . . . . . . . . . . . . . . .   3
   4.  Configuration Guidelines for the Server . . . . . . . . . . .   4
   5.  DHCPv6 Client Behavior  . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Several solutions (e.g., [I-D.ietf-softwire-dslite-multicast]) are
   proposed for the delivery of multicast services in the context of
   transition to IPv6.  Even if these solutions may have different
   applicable use cases, they all use specific IPv6 addresses to embed
   IPv4 addresses, for both multicast group, and multicast source
   addresses.

   This document defines a DHCPv6 option [RFC3315] to convey the IPv6
   prefixes to be used for constructing these IPv4-embedded IPv6
   addresses.

   This option can be in particular used in the context of DS-Lite
   [RFC6333], Stateless A+P [RFC6346] and other IPv4-IPv6 transition
   techniques.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].








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2.  Terminology

   This document makes use of the following terms:

   o  IPv4-embedded IPv6 address: is an IPv6 address which embeds a 32
      bit-encoded IPv4 address [RFC6052].  An IPv4-embedded IPv6 address
      can be a unicast or a multicast address.
   o  PREFIX64: is an IPv6 prefix used for synthesizing IPv4-embedded
      IPv6 addresses.  A PREFIX64 can be of unicast or multicast.

         Note: "64" is used as an abbreviation for IPv6-IPv4
         interconnection.
   o  ASM_PREFIX64: is a multicast PREFIX64 which belongs to the Any-
      Source Multicast (ASM) range.
   o  SSM_PREFIX64: is a multicast PREFIX64 which belongs to the Source-
      Specific Multicast (SSM, [RFC4607]) range.
   o  U_PREFIX64: is a unicast PREFIX64 for building the IPv4-embedded
      IPv6 addresses of multicast sources in SSM mode.

3.  PREFIX64 DHCPv6 Option

   OPTION_V6_PREFIX64 (Figure 1) conveys the IPv6 prefix(es) to be used
   (e.g., by a mB4 [I-D.ietf-softwire-dslite-multicast]) to synthesize
   IPv4-embbedded IPv6 addresses.

      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        OPTION_V6_PREFIX64     |         option-length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  asm-length   |                                               |
     +-+-+-+-+-+-+-+-+                                               :
     :                  ASM_PREFIX64 (Variable)                      :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  ssm-length   |                                               |
     +-+-+-+-+-+-+-+-+                                               :
     :                  SSM_PREFIX64 (Variable)                      :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | unicast-length|                                               |
     +-+-+-+-+-+-+-+-+                                               :
     :                   U_PREFIX64 (Variable)                       :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 1: DHCPv6 Option Format for PREFIX64

   The fields of the option shown in Figure 1 are as follows:

   option-code:  OPTION_V6_PREFIX64 (see Section 8).
   option-length:  length of the PREFIX64 option.



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   asm-length:  the prefix-length for the ASM IPv4-embedded prefix, as
      an 8-bit unsigned integer (0 to 128).  This field represents the
      number of valid leading bits in the prefix.
   ASM_PREFIX64:  this field identifies the IPv6 multicast prefix to be
      used to synthesize the IPv4-embedded IPv6 addresses of the
      multicast groups in the ASM mode.  It is a variable size field
      with the length of the field defined by the asm-length field and
      is rounded up to the nearest octet boundary.  In such case any
      additional padding bits must be zeroed.  The conveyed multicast
      IPv6 prefix MUST belong to the ASM range.  This prefix is likely
      to be a /96.
   ssm-length:  the prefix-length for the SSM IPv4-embedded prefix, as
      an 8-bit unsigned integer (0 to 128).  This field represents the
      number of valid leading bits in the prefix.
   SSM_PREFIX64:  this field identifies the IPv6 multicast prefix to be
      used to synthesize the IPv4-embedded IPv6 addresses of the
      multicast groups in the SSM mode.  It is a variable size field
      with the length of the field defined by the ssm-length field and
      is rounded up to the nearest octet boundary.  In such case any
      additional padding bits must be zeroed.  The conveyed multicast
      IPv6 prefix MUST belong to the SSM range.  This prefix is likely
      to be a /96.
   unicast-length:  the prefix-length for the IPv6 unicast prefix to be
      used to synthesize the IPv4-embedded IPv6 addresses of the
      multicast sources, as an 8-bit unsigned integer (0 to 128).  This
      field represents the number of valid leading bits in the prefix.
   U_PREFIX64:  this field identifies the IPv6 unicast prefix to be used
      in SSM mode for constructing the IPv4-embedded IPv6 addresses
      representing the IPv4 multicast sources in the IPv6 domain.
      U_PREFIX64 may also be used to extract the IPv4 address from the
      received multicast data flows.  It is a variable size field with
      the length of the field defined by the unicast-length field and is
      rounded up to the nearest octet boundary.  In such case any
      additional padding bits must be zeroed.  The address mapping MUST
      follow the guidelines documented in [RFC6052].

4.  Configuration Guidelines for the Server

   DHCP servers supporting OPTION_V6_PREFIX64 should be configured with
   U_PREFIX64 and at least one ASM_PREFIX64 or one SSM_PREFIX64.

   When ASM_PREFIX64 and SSM_PREFIX64 are configured, the length of
   these prefixes must be /96.

   Both ASM_PREFIX64 and SSM_PREFIX64 may be configured and therefore be
   returned to a requesting DHCP client; it is deployment-specific.  In
   particular, if both SSM and ASM modes are supported, ASM_PREFIX64 and




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   SSM_PREFIX64 prefixes must be configured.  For SSM deployments, both
   SSM_PREFIX64 and U_PREFIX64 should be configured.

5.  DHCPv6 Client Behavior

   To retrieve the IPv6 prefixes that will be used to synthesize unicast
   and multicast IPv4-embedded IPv6 addresses, the DHCPv6 client MUST
   include OPTION_V6_PREFIX64 in its OPTION_ORO.  If the DHCPv6 client
   receives more than one OPTION_V6_PREFIX64 option from the DHCPv6
   server:

   o  If all the enclosed IPv4-embedded IPv6 multicast prefixes have the
      same scope, the first instance of the option MUST be used.
   o  If each enclosed IPv4-embedded IPv6 multicast prefix has a
      distinct scope, the client MUST select the appropriate
      IPv4-embedded IPv6 multicast prefix having a scope matching the
      IPv4 multicast address used to synthesize an IPv4-embedded IPv6
      multicast address.

   If asm-length, ssm-length and unicast-length fields are all set to 0,
   the DHCPv6 client MUST behave as if OPTION_V6_PREFIX64 had not been
   received in the response received from the DHCPv6 server.

   If the asm-length field is non-null, the IPv6 prefix identified by
   ASM_PREFIX64 is used to synthesize IPv4-embedded IPv6 multicast
   addresses in the ASM range.  This is achieved by concatenating the
   ASM_PREFIX64 and the IPv4 multicast address; the Pv4 multicast
   address is inserted in the last 32 bits of the IPv4-embedded IPv6
   multicast address.

   If the ssm-length field is non-null, the IPv6 prefix identified by
   SSM_PREFIX64 is used to synthesize IPv4-embedded IPv6 multicast
   addresses in the SSM range.  This is achieved by concatenating the
   SSM_PREFIX64 and the IPv4 multicast address; the Pv4 multicast
   address is inserted in the last 32 bits of the IPv4-embedded IPv6
   multicast address.

   If the unicast-length field is non-null, the IPv6 prefix identified
   by U_PREFIX64 field is used to synthesize IPv4-embedded IPv6 unicast
   addresses as specified in [RFC6052].

6.  Security Considerations

   The security considerations documented in [RFC3315] and [RFC6052] are
   to be considered.






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7.  Acknowledgements

   Particular thanks to C. Jacquenet, S. Venaas, B. Volz and T. Taylor
   for their review.

8.  IANA Considerations

   Authors of this document request IANA to assign a new DHCPv6 option
   in the registry maintained in http://www.iana.org/assignments/
   dhcpv6-parameters:

                                   Option Name    Value
                                ----------------- -----
                               OPTION_V6_PREFIX64 TBA

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC4607]  Holbrook, H. and B. Cain, "Source-Specific Multicast for
              IP", RFC 4607, August 2006.

   [RFC6052]  Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
              Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
              October 2010.

9.2.  Informative References

   [I-D.ietf-softwire-dslite-multicast]
              Qin, J., Boucadair, M., Jacquenet, C., Lee, Y., and Q.
              Wang, "Delivery of IPv4 Multicast Services to IPv4 Clients
              over an IPv6 Multicast Network", draft-ietf-softwire-
              dslite-multicast-06 (work in progress), October 2013.

   [RFC6333]  Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
              Stack Lite Broadband Deployments Following IPv4
              Exhaustion", RFC 6333, August 2011.

   [RFC6346]  Bush, R., "The Address plus Port (A+P) Approach to the
              IPv4 Address Shortage", RFC 6346, August 2011.




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Authors' Addresses

   Mohamed Boucadair
   France Telecom
   Rennes  35000
   France

   Email: mohamed.boucadair@orange.com


   Jacni Qin
   Cisco
   China

   Email: jacni@jacni.com


   Tina Tsou
   Huawei Technologies (USA)
   2330 Central Expressway
   Santa Clara
   USA

   Phone: +1 408 330 4424
   Email: tina.tsou.zouting@huawei.com


   Xiaohong Deng
   APNIC
   Australia

   Email: dxhbupt@gmail.com



















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